PMID- 3026443
OWN - NLM
STAT- MEDLINE
DCOM- 19870227
LR  - 20190613
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 25
IP  - 22
DP  - 1986 Nov 4
TI  - Direct incorporation of guanosine 5'-diphosphate into microtubules without 
      guanosine 5'-triphosphate hydrolysis.
PG  - 7054-62
AB  - Using highly purified calf brain tubulin bearing [8-14C]guanosine 5'-diphosphate 
      (GDP) in the exchangeable nucleotide site and heat-treated microtubule-associated 
      proteins (both components containing negligible amounts of nucleoside diphosphate 
      kinase and nonspecific phosphatase activities), we have found that a significant 
      proportion of exchangeable-site GDP in microtubules can be incorporated directly 
      during guanosine 5'-triphosphate (GTP) dependent polymerization of tubulin, 
      without an initial exchange of GDP for GTP and subsequent GTP hydrolysis during 
      assembly. The precise amount of GDP incorporated directly into microtubules is 
      highly dependent on specific reaction conditions, being favored by high tubulin 
      concentrations, low GTP and Mg2+ concentrations, and exogenous GDP in the 
      reaction mixture. Minimum effects were observed with changes in reaction pH or 
      temperature, changes in concentration of microtubule-associated proteins, 
      alteration of the sulfonate buffer, or the presence of a calcium chelator in the 
      reaction mixture. Under conditions most favorable for direct GDP incorporation, 
      about one-third of the GDP in microtubules is incorporated directly (without GTP 
      hydrolysis) and two-thirds is incorporated hydrolytically (as a consequence of 
      GTP hydrolysis). Direct incorporation of GDP occurs in a constant proportion 
      throughout elongation, and the amount of direct incorporation probably reflects 
      the rapid equilibration of GDP and GTP at the exchangeable site that occurs 
      before the onset of assembly.
FAU - Hamel, E
AU  - Hamel E
FAU - Batra, J K
AU  - Batra JK
FAU - Lin, C M
AU  - Lin CM
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (Carbon Radioisotopes)
RN  - 0 (Guanine Nucleotides)
RN  - 0 (Microtubule-Associated Proteins)
RN  - 0 (Tubulin)
RN  - 146-91-8 (Guanosine Diphosphate)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - EC 2.7.4.6 (Nucleoside-Diphosphate Kinase)
SB  - IM
MH  - Animals
MH  - Brain/*metabolism
MH  - Carbon Radioisotopes
MH  - Cattle
MH  - Guanine Nucleotides/*metabolism
MH  - Guanosine Diphosphate/*metabolism
MH  - Guanosine Triphosphate/*metabolism
MH  - Kinetics
MH  - Microtubule-Associated Proteins/*metabolism
MH  - Microtubules/*metabolism
MH  - Nucleoside-Diphosphate Kinase/isolation & purification/metabolism
MH  - Tubulin/*metabolism
EDAT- 1986/11/04 00:00
MHDA- 1986/11/04 00:01
CRDT- 1986/11/04 00:00
PHST- 1986/11/04 00:00 [pubmed]
PHST- 1986/11/04 00:01 [medline]
PHST- 1986/11/04 00:00 [entrez]
AID - 10.1021/bi00370a045 [doi]
PST - ppublish
SO  - Biochemistry. 1986 Nov 4;25(22):7054-62. doi: 10.1021/bi00370a045.